Silane coupling agents based on the organotrifunctional silanes are now well-known. The silicon portion of these compounds have a unique affinity for glass, aluminum, steel and similar substrates. These compounds are commonly employed to establish chemical bond between organic polymers and inorganic materials. For example, they are ordinarily added to organic polymers intended to bond to inorganic fillers or surfaces. In contrast thereto the present invention instead of employing these coupling agents in the conventional manner, takes advantage of their trifunctionality and ability to form crosslinked siloxane coatings. More specifically, it has now been found that certain organic hydrolyzable silanes having a functionality greater than 2 can be applied to particulate high energy solid rocket propellant ingredients to form thereon coatings of an organic crosslinked siloxane polymer which provides a free-flowing product. In addition, the use of the coated particles in propellants has quite surprisingly been found to increase the burning rate of the propellant.